Method of making lenses



0t.19,1943. J. A. MORI-:HEAD 2,332,246

METHOD OF MAKING LENSES Filed May 51, 1939 2 Sheets-Sheet 2 APatented ocr. 19, 1943 f assaut yThis applicationis a continuation in part of my application, Serial No. 235,685,I now Patent No. 2,287,191, issued- Jujne 23, 1942.

This invention relates to optical apparatus and Vmethod o'f making the'same and, more particularly, to f the portion ofthe optical apparatus which directs rays of 'light in'the desiredmanner,

namely, to the lens; Y

' The Apresent invention is concerned, more specically,1wit-h autocollimating reflectors such as are used, for instance, on highways/and on auto- 'mobiles or other vehicles.` The object of such reflectors is to reiiect lightV from vthe-headlights-of an ap-proaching'vehicle back towards the source with an amountof spread only sufficient toenable the reflected. light to reach the line of vision "of the driver of the approaching Vehicle even Y though `the light mayfstrike thel reflector', from various Vangles Within a Wide range.

'proved highways and consequent higher andwf Withv inlhigher automobile speeds it becomes more Vand more necessary to have V'such reflectors Which are capable of reflectingalarge amount of light for very great distances in a direction substantially parallel to vtheincident b eam. i The legal require' ments in many instances are such that the relfiected iight from the headlights 'cf an approach- 'ing" vehicle'must be of a'specied intensity to be clearly visible ata distance ofy three hundredfeet or' more. This necessitates a high degree oflprecision in the curvature of the reflector-thereby,

` of course,` increasing the! cost of manufacture of the' unit'.

` lf Consider, vbyu-ray" off example, an autocollimating-reflector of the `type shown, for instance,- in

lligure' 3 of thepatent to Chretien,Ressue No.

19,676. glass' l-vvith contrex surfacesv at its two ends, vthe radii cf'v'the tun/'osurfaces beng differentandf'of f relative lengths a'sfdetemined byv knownl optic laws, and the centers ofculvature both positioned This comprises essentially a block of on Athe same optical axis.- Any deviation ri'n'fthe j 'curvature of the reectin'g surface will result in al diminutio'niofth'e reflectedlight in th desired direction. At a great distance this dimir'iu'tionk is so great as to 'render the reflector' unsatisfactory, even though the deviation fromthe correct curvature? is very very small.

' In" the r`maniIrfacture of va comparatively large f reflecting butto-'nz ofthe type referred to aborvef such as is necessary where 'a large amount of reectedlight is required, `vthe shrinkage or other distortion of the large mass `of molten glass before fit soiidies is sufhcient to cause sucha degree cfm i inaccuracy Lin 'thev curvature of `oneier .more-'of'` 55--curvaturefapproximatelyfbut not quite the-requithe lens surfaces as'to'rendervthe'button useless 'in'mostinstances unless'it is vsubjected to grind- Ving or other operations to bring itto the requisite curvaturefThis defectibecomes more and'ino're serious as the size of the reflector button being manufactured is increased. It isf'one of the objects of lthe'present invention to' provide a method .oftmakin'g large"r reflector buttons fof the above mentionedicharacter, in two stages, the first stage of which aims to form the reflecting surface, or the surface which becomes' distorted, to'ap-proximately but not 'necessarily'of quitethe' requisitel shape, said surface having less' glass than' required rather thanfmor'e glass'.` Therefore the 'surface must be built up to therequisiteshape-'insteadfof vhaving to be ground 'down tol'ther'equisiteshape.

' rTnisunit, when quitehot burst-ineens, is placed l I m'tnshesasthe thickness rof the button and inrjter'1sity"of` the lcolored glass is increased. Y On A"large, reflector buttons Where there is yan appre- Within the glass reflectorl button becomes 'apprev thinnessg absorbsy substantially.` no light;- The l `vvhich ithas been molded by the die.A Reectorbuttong ythatare' to reflect light" inin a mold and a layer of molten glass pllaced over it. 'Adie then p'resseSthe'layer-of molten glass to the requisiteshape .so`A that "the-newly 'added glass forms a thin nlm which is'fused to the pre- 4fviousl-yformed reflector button andforms anfin- N,teg'ral part thereof. Upon retraction of thede,

or" cooling of 4the thin liilm of" glass, ther total 'amount'of molten Yglass thatfis subject to change 'in vshape is so slightfthat the v'change in shape of the finished-reflecting surface isnegligible and the surface' cools-'to substantially theshape to dicative ofdang'ershould be of afred color, since red isthe `accepted color for indicating danger. Red glass necessarily 'absorbs a good deal more light thanl-clear transparent glasslab'sorbs hence a'red ree'ctor button 'is less efcientthan i'sa clear glass lreflector button; The eiciency, di-

ciable thickness of glass'this absorption off-'flight ciablel TI have discovered-'away of making an `vautocollimating-refiector of "the above character 'which will have llight absorption characteristics not appreciably'differentfrom vthose of "a Aclear glass 'reflectorL and yet Will re'ect red (or any Y other desired Icolor). l forming thelreflector button" of clear glass and i then molding athin nlm-like layer of colored 'over'the' back reflecting surface thereof.

This is!` accomplished vby This" thin layer imparts the necessary colorY to the reflected light and, lbecause of its extreme l' clear glass-rflector'- button may `Vbe' molded; to-a that 'of the surface 3.

fleeting surface of approximately but not quitA the requisite shape and that buttor'r then. placed in a mold and Va body of molten glass molded around the vsame to form the rest ofthe'autoinfv bile stop or tail light lens and during' 'that' inblding operation the thin lm olf 'glass required for bringing the reflector button curvature to the requisite shape may be molded in place.

The attainment of theabove and further ob- .j'ects of the present invention will be `'apparent from the following specification taken in conjunctionwith the accompa-nying'dr'awings forming a partthereof In lthe drawings:

Figure l is a sectional view of a reflector insert tobe molded into an automobile tail lamp lens;

Figure 2 is a longitudinal sectionalv view through a die embodying the present invention;

Figure-3 is a plan view of the die of Figure 2;

Figure 4' is a top view of the ring and mold of the die of Figure' 2;

Figure 5 Yis a sectional view through a lens formed by the die of Figure 2';

1 Figures 6 andi' are fragmentary sectional views at right anglesto one another of another die;

and

quired. To obviate this difficulty the reflector button I is therefore made so that the surface 3 is of the exactly required curvature and the top surface 9 is of approximately but not necessarily the requisite curvature. The button I may be made in any desired manner, as by molding or pressing, or in any other way. The space between the dotted line 6 and the full line 9 representsftheextentto which the `back surface 9 of the cast reflector button deviates? from the ultimatelyY requisite surface. In accordance with the teachings of the present invention a thin layer of glass I0 is then pressed over the surface 9' in 'such a way that the added glass Iil fuses with the body of glass 2 into one integral struc- `If'tu're. vAny shrinkage of the fused glass I0 may c'a'use thesurface B to deviate a slight amount lfrom' the surface of the die used in forming the surface 6 but, because the layer of glass I0 is Very thin, from a few thousandths of an inch to a ythicknessf of the order of a few tenths of an inch, fthe total shrinkage will necessarily be so very small as not to affect the accuracy of the ultimate lens. `The body ofglass- 2 may be glass of one kind as, for instance, crystal clear glass, and the glass layer I0 may be of a different color as, ,for instance, amber or ruby colored glass, so that white light striking the surface 3' and passing through the reflector and then back out again at the surface 3 will be of the requisite color.

.After completion of the glass part of the lens the surface 6 is silvered to facilitate the reflection of light throughthe lens.

An explanationv will now be given of the construction of thepdies for forming a lens of which the' precastr button I is a part, the layer of glass I0 being, formed on' the precast button I during Figures 8Y andll are plan and side views of anand it is to be understood that this term is being used in its broadest 'sense to include any plastic ormoldable light transmitting material;

In the construction of autocollimating reflector buttons such as are shown, forfinstancefin Figure 3 ofthe patent to Chretien, ReissueV No.

19,070, or as shown in my pending application Serial No.- 235,6 85, now PatentNo; 2,287,191, is- -sucd June ;2-3, 1942, it is essential that opposite curved surfaces of the reflector should be: of exactly the requisite radius of curvature and the requisite distance apart.y Consideryby way of example,- an fautoc'ollimating reflector button ,a cross section of which lis shown in- Figure .lg The reflector button I consistsof a body 4of glass v 1' circular' in cross section throughout. This button must be so constructed that if; will reflect v.light in the form of a beam substantially parallel toan incident bea-m from varying angles, but with a very slight spread. `For this purpose it is essential that the spherical surface 3 should have its center along the optical axis -and that the Opposite spherical surface, indicated-by the dotted -line 6; should also have .its center on the same optical axis 5 but beef a differentl radius than It is essential that the,

distance `between vthe surfaces 3 and 6 shouldbe a predetermined amount. In making this reflector by pressing molten glass between a pair of dies in a single operation it is exceedingly difficult to obtain thecu-rvatures 3 and 6 exactly as re-,-,

the prcces'sfof vforming of thel rest of the lens.

.' Ihe' diecomprises a' mold I2 adapted to receive `aring I3 and a plunger .I4v mounted in a press (not shown) and arranged to be moved down into' the ring I3 to press the 'lens to the requisite shape.' The mold- I2 is made of cast iron 'or the `like and includes a cavity I-5 having the shape of therexterior of the ultimately finished auto* mobile .flens to be made, and it also includes a cavity II` of exactly the requisite shape to receive the reflector button I and 4hold the same snugly.

A1 precast reflector button I can be placed in the rcavity I6 with the surface 3 of the reflector button; resting on the similarly curved surface I3 of the cavity IB,-and the axis I9 of the cavity I6 ycoinciding exactly with the axis 5 of the button.

.It vis to be noted that the,l cavity I5 in the mold I2 and the cavity I6 thereof are at suchanangle to; the horizontal that the ultimately cast lens vis in a slightly inclined position in the mold.

This facilitates the flow of the molten glass under the pressing action of the plunger or `male die, as Will be more fully described. The'mold I2 has a handle-'I1 secured thereto to facilitate handling of the mold.

The mold cavity I5 includes a portion 20 adapted to form a peripherally extending rim around pletion of a pressing operation. The ring I3 has 4the lens.

'The -ring I3 fits snugly into the mold I2. A

space 20 so that the ring I3 prevents the plunger from drawing the cast lens up with it when the plunger recedes from the mold I2 at the comr an opening 22 therein of exactly the same contour as that of the plunger I4 so that the plunger slides smoothly through the ring I3. I.757-

The ring hasa peripherally extending flange 2 3 to facil- "those holes theplunger-"BI Anex'planatio Wil nowbegiye'n tithe-man-J "ner of forming a lenslin accordance with the' f present 'inwenti-0fi,y f button Ijoith sha andhaving a top but not exactly `first formed. Thev 'surface'. s isatsuch a distance itaterremovalfof the' ingeffrorn ethe mold ;and -i lreliiserti'on ,'fthereof f int. the rmoldl. LThis; ange 223s alsohas the additional .function yrofl. acting: as a. stopfora part` o'frthey male -die'oztplui'ger I4 as will be.` more fullytset; forthyasithis descrip` i .tion vpr.oceeds.'.-. The ring..'.f|f3 has`ia largeifnumber rof small holes '2 5xfo'rmed thereinzaround the open- I ing j22 Vso thatthe 'thicknessoffmet'alifrom the surfaceg22 to .the ho1es..25vis.q^uite ;sr'nall'.; This `reduces the heatstorage capacityo'v the 'ringjand a inhibits ltheflow;..of.I heat .romlthe v`surface 22 vinto the bodyrof cmetall.of;.the.ring..l.3 :.The'surface 22 therefore remains; hotterg-.tlianitf .Would without the -:l1o1es,..;and Lth'ereforezhasfa lesser el hea-@3.3 .has analoge .I4 by tWO f Powerful: 'sprinesaeffltthat y bear :at

their. lcwcrcnds aaainstthcfripe 4.2 and at their Yupper enlSnagcinst tbe rcrinbcrally extending .flange M .onutheliead 38. q'.1.'11e;plunger 3| is f rigidlyA @01111cctcclf..to` the.. irme: 4-2 in; any. desired manner, as b yca r p in 4L-that .extendsthrough thel .ring` andthro gli ane`t e11si on y 4 8 whichis an f extension `18Tis.au idg-:du:in;a. slot- ,4 9 formed in the flange 14- .Afpini .50. is) threaded. atrits flower endfinto the ringe? and spring/ 44 and is' uid @d ai'. tss. uppelcend inra rsame predetermined' fixedv distance from the ring adjacent, the, pin bolts 54 and `55 the, ring. 4.2 :since pacedfro1n `t he portion 4 8 .vof

"b vseen om Figure 3.;

may ybe `on the top surface .precast .or pressed glass illustrated ,inf'Figure 1, l rted surface 9 approximately 1 ofjthe 1"`equisite,curvature 6 is from the surfaced thatit has to be builtqllp to the requisite surfacelli .rather -than be :ground to .the surface 5.'. The preformed glass f button I, isheatedtoa temperaturebelowthat at Wl'iicli "softeningfof thef'glass 'takes-place; but suiciently -high to permitgfusicn of -thevbutton Withf-the 'rest ofthe lens to be form ed-andto avoid .cracking or unduly'straining .lieglasg ofythe .button or the glassto becfornediadjacent thereto and f'used"therk-Jto f The; lbutton; lIV is then placed in thev cavity thefniold .I2z with the surface 3 .oflthe button Q Wermostq The inold may be pressing 'face 3 0 i .dispensablelf Thereafter Aamass .ofV.-niolten fglass inananiountl'suflicint' toY form the len's is `placed I into; .thefm'ld .cavity I5.` @It.,is'-.desirab1ev that the .elevated.'tem'perature ofithef button 2 betas low as. possible but lsui'liciently high-to aVoid::cracking '.'asfthes mass; of Avmoltenglass comes in conta'ct f andf cooling /of-.th/ e molten mass.`

therewithiancl upon the subsequent.; solidilication The. ring. :I3

1 is'. then placed in .Y thev mold*I2, intheyposition f iin 'the' press.

.. illustrated in Figure. 2'.2;1Themold is thenv placed 60 and is .providedwith a circular .curved surface 6 I; which 'ts` an opposit'ely curved o'r concaveacedplate in the press.` Abolt 62e-xtendingfro'm z the mo'ldnis broughtagainst af'stop in the press, thus definitelyl centering theymold Ain the press.

c er 3Ij is injth'e exact; positionzjfor forming-the `The` plunger Mis` thenlowered, rst .into the ring andtheninto themold I2.. :The plunger descends as a unit until the heads 58 orxthefboltsiabut reachesthisipsition the surface 3 3 of: the plungy of the spherical curve," 1.33 :coincides withv the axis I9 :of thefspherical curve LIB, and the curved j surface 33'isatgexactlyfthe correct distancezfrom the curved surface; I8.V v-I1hiSplaces 4-tlfie curved surface 33e. atya :veryrlight distance from the vcurved .surface 'Iliis distance .may 4be; anywhere from a LfeWf hundredths; of= anQinch-tosa `v'fewftenths o f an'incln'.r :The moltenglass Von the surface Stof thebutton `I -is thus-pressed' to the requisite shapey by; the plungerl; ItA is,"how

Aleven-'not indispensable thatthe'molten lglass be vO11 .thebuttonntat thetime the plunger 3 I reaches -itsilowerrnost position; althoughlth'at is'the-'preferred' condition,l press Yoperator Continues lowering. thcrlimeerl I4; thefplurleerf 3l at; 'this time remainingl j stationaryg-until he v fgeels the vproperamount of back4 pressure resisting. further i .plunger zliniitsfdcsccnt has. 'prcssedfthcfmass cf molten 1- glass i10- -thcfcquisite chape. r`and-.if 1 there-was; norglass `initiallyfloetween the surface i: @Spot-the plunger j3 I and thesurfaceySx-O rthe buiten I. thciiurthcr .descent cf the plunsecl forces the molten '..glasscinto the vspace between `the blutiger 3l andfthegbutwri, i :The glass.A iS thus pressed imc. the requisite .chape Infthus forming the lens it is notessential tliattthe the th-iCkileSS @Mba .buiionfbctwccn 'thcciirface .Sand the `surfac d gDuring the pressing Aofthe glass the, springs 3444, exert; suioientgpressure upecihc plat@V 42 and thus upon the plunger.v 3 IV v .to prevent the' pressure.. of.l tneslass. from lforcing :QTL which is v locatedV on t fzontal directionrf The comprlsesa .body ofV .glassdhaving theelear [glass vi1is er t.l `I. Inoldedftl'iereinrand iunited to vthe main body o fk red glass byt e thinlayer of glass In" .order-to center :the :mold in the press the bottor'nof the mold .is recessed at s placed in the .nqloldsliould be gdeterrninedc'w h y extremeprecisi`on.' Any Slightly. srcatcr aclrf lesser; @mov-nt: off-molten glass placed'inftbejinold |55 Will result. in a slightly f thicker 0r.. ,thinner 'lens :1 body-.but .can y.nctfarfcct mal position, as uiustraned in Figures. A layer of reflector buttons.

of silve'ring material E3 is formed on theback 'of the lens 65 at the4 insert I to refiect light forward of the lens of Figure 5. A ray of light striking the button I from any angle. within prescribed limits will pass through the button, through the layer of glass I0, to the mirror reflecting surface 6a. Fromthe surface 69 the 'ray of light will be reflected back through the layer of glass I and the button I to emanate from the button in a direction substantially parallel to the incident beam but with a very slight spread. The light from the headlights of an approaching automobile will be reflected back by the reflecting surface 3s withsufiicient spread to reach ythe eyes of the driver of the approaching automobile. The

- back ofthe mirror reflecting surface 69 may be coated with a paint, such as aluminum paint, .orfother preservative to protect the mirror reflecting surface. i

The mold I5 is formed' with the button receiving cavity I6 at a substantial vangle to the vertical` This is due tov the fact thatl the lens is moldhad been formed in a position rotated in a clockwise direction from that shown there would be difliculty in forming theFresnel projection 66.

`While I have here described a set o1' dies and a process for making a lens having a single refleeting button, it is to be. understood that the principles of the present invention are applicable to the manu-facture of alens having a plurality would have a plurality of cavities corresponding to I6, each for receiving a precast reflector button, and thel plunger |4'Would have aplurality of individually movable plungers 3|; one for each reflector button. All the lplungers 3| may be se- In that case the mold I2 f f castv glass button Figure 2, the heads; of the bolts 13 ultimately engage the flange 23 ,of the ring and thus limit further descent of the plunger 3 I. As the plunger I4 continues to descend', the plunger 3|' remains. stationary. the plunger I4" sliding on the plunger 3|. The plunger I4^`presses .the glass to the requisite shape while the plunger 3| forms the thin Ilayer of. glass I0 (Figs. 1 and 5) to exactly the requisite shape and at exactly the requisite distance from the surface 3 of the pre- In other respects this die andthe pressing operation are the same as in the embodiment previously described.

In Figures 8 and 9 I have shown, diagrammatically, a cast glass reector having a plurality ofbuttons as an integral part thereof. The buttons are indicated by the reference numerals 80. This reflector unit may be formed by placing a plurality of buttons, in this instance eight, into suitably formed l' cavities in a mold and then 'placing a body of molten Vglass into the mold, in vthe manner above set forth and molding the thin surfacing layer III (Fig. 1) yover the `bodies by means of a plunger corresponding Vto the plunger f struction the button receiving cavities in the cured to theV stop plate 42 or each plunger may be provided with an individual stop to limit its downward movement into the mold. Thereafter the continued downward movement of theplung- In Figures 6 and "I I have shown a fragmentary portion of a maledie or plunger of a construction somewhat different from that of Figure 1. In this construction the plunger I4", which correspends to the plunger I4 of Figure 2,` includes a cylindrical part 10 integral therewith for mountthe bore 32 of theV plunger, I4', being" pressed downwardly by a very powerful spring 1I that bears at its lower end against a plate 12 that is secured to the plunger 3| and at its upper end against an L-shaped bracket 14 that is suitably securedto the cylindrical part 10 ofthe plunger I4'. The plate 12 has a pair of stop bolts 'I6-I6 threaded therethrough and locked in position by lock nuts 'l1 so that the` heads ofthe bolts I6 constitute adjustable stops in exactly the same manner as do the heads 58 of the nuts 54, 55 and 56 in the embodiment previously described. Upon descent of the plunger I4', and withit the plunger 3|', into the ring I3 of the mold I2'of er I4 'presses the molten glass into the spaces between the precast buttons and the curved surfaces `33 of the respective plungers 3|.

, the respective buttons.

down rupon the mass of molten 'glass'.

mold', correspondingV to the cavities I6, are formed in the mold with their axes, corresponding to the axis I9 of Figure 2, vertical. The correspondingk axes ,35 of the respective plungers forming 4the layers III are therefore also vertical and in alignment with the axesy of the button cavity in the female or mold part. When the molten glass is pressed around the buttons a "body of glass 85; which is of'the material of the glass IIJ, is formed which is fused to and connects If it is desired to make the surface 9 approach more closely the requisite surface 6, the molded article may be, left in the mold to solidify and partially cool and then an additional layer of molten glass may bel pressed over the same. Thereafter the back surfaces 6 of the respective buttons may be silvered to facilitate light reflection.

The'process outlined above for the manufacture of thereflector bodyl of Figures 8 and 9 may be used for forming the buttons I. In this procl ess no precasty buttons are placed into the button receiving cavities.

y Instead a` mass of molten glass is placed in the.r mold'and a plunger I4 with its individually'movable plungers 3| is brought The quantity of glass placed in the mold is such that the overflow from the buttons, represented by the Athickness of glass at 85, would be very small.

The resulting product would be a series of buttons such as illustrated in Figure 1, joined by a thin fin of glass 8 5. The buttons. mayy then be broken away from the fin to provide the individual buttons for use in the mold of Figure 2, or for such other use as may be desired.`

vFrom the above description it is apparent that the principlesof the presentl invention maybe appliedfto the manufacture of glassware wherever it is 'desired to make an article of pressed glass having a xed andfpredetermined thickness at any determined place or places. If an article 332,246 of that type is molded-by a die suchjaszis i11us`- trated in ligure 2;/withfor without a precvzast'y insert, the body of glass, opposite.; the nfiov'a'blevl plunger 43l will be 'cfa thickness asi desired even;

though a greater or lesser yamountwof molten... glass may have beenplaced" in the' mold by the,

operator.y Ifa slightly greater amount of glass. is' used. the overow, material "will `result in an thicker body of pressed glass Without increasing'" the thickness of the glass opposite the plungcr 31.., 1Likewiseif a slightly'flesser amount oiglass isplaced in the mold the; resulting piroducttv'ilrV besomewhat thinner throughout; exceptfatvthe place wherethe plunger 3|;engages the `lcody'of` glass. Furthermore the main plunger lll-presses the molten glassy into intimateengagementWith-.- the surface of the plunger 3| so that the surface ofthe glass at that place is of the shapeexactly- Y as determined bythe shape ofV the plunger, al1o w ing forgdeviations as thezglassshrinks frorntheA 20 lIn compliance with the requirements ciY theY patent statutes I'have here shown and described' t ariete-'preferred embodiments of my invention. It is,` however, tobe understoodthat the invenfj tion is not' limited to the precise constructionsv 'f here shown, the 4same being merely illustrativeA oi the principles ofthe invention. What I consider new and desire to, secure by Letters :Patent isi:

Il. The method of making a lamp' lensu^"f0r` transmitting light'of a dan-gerindicatingcolor and .for'reiiecting incident light in the :generall direction .of the light sourcevbut with a*slight` spread andfimparting the danger-indicatingcolor to the" reflectedv'light, which method comprises,Y forming' an autocollimating lens part insert ofc.

colorless `lens forming material'with one surface thereof of 'the requisite curvature and` the'oppo.

site surface of not quite the necessary f locationV for autocollimatingreflection, Vthe deviation being one of lunder-size, placing said'formed part ina`V mold'.` 'then .molding colored light transmitting.- lens-forming f material around `said' preformedfl part' 'to constitute the light-transmittingk portion' ofthe lens'alnd in said molding operation forming. a layeriof said colored lens-forming materialfoverf y:

said opposite. surface to bring said oppositezsurfc-r .face to exactlythe requisite shape andlocationr. with respect to said one rst mentioned. surface;

said'layer being formedcf ajthicknessless than*A the averagevr thickness of ;the light transmitting,

vportion ofthe lens so .that the colored z-layenwll? impart tlie'requisite danger "indicating-color.'toy;

reflected light passingthroughithe clear.. glass insert.` 1 .2. VThe method of making `a lens fortransmi ting light of a danger indicating color and forf' reflecting incident light inthe general directionof the lightsource but with a slight spreadandimparting the `danger indicatingv colorjto y'there-1.1 flected light; which method comprises forming -z a block of transparent lens-forming material with one surface thereof of the requisite curvature toi,l

form' the reflecting portion rof the lens andfwithj the oppositesurfacedeviating from'the necessary i `r shape and locationior autocollimating:reiiectioni the deviation being one of undersize, placingsaid block ina mold with its accurately formed, sur.:-y

face in engagement: with the mold` Wall and its opposite surface in the mold cavity, placing vva mass of molten glass ofca danger indicating color'- in said mold cavity, bringing' a'moldingplunger.

into a positinfspaced" from and opposite to saidV opposite surface of the blockv and pressing molten glass between the block andthe plunger-t0"buildV up the said opposite surface to the requisite shape and distance fromt the rst mentioned surface of theblock toreflect incident lightin the general direction'ofthe light source. but', with aslight spread.

3.:The .methodof. making a lamplens forv transmitting light of adanger vindicating color andiiorv reectingf incident light in .the'general direction .of rthe f' light source but' v/ithza. slight spread andirnpa'rtingthe danger indicating color. to .thee reflected light; which method comprises' forming a blockitransparent lens-forming ma. terial with onesurface. thereoifof .the requisite curvature toform thereflectingl portion. of the l lens and with the opposite surface deviating from thernecessary shape and location.' for autocollimati'ngfreectio'n; the. deviation being one 'of undersize; placing said block'in' amold with its 'accurately .formed surface'. inlenga'gement -livith ;v

the moldwalliandxits'opposite 'surface in the-moldcavity, placing `a mass oit molten glass of a danger..A

indicating. :color .in saidlmol'dflcavity, bringingia I molding plunger .intol' ail position' spaced. from and opposite.' to v'saidfopposite surface of 'i the 'blockflf bringingfLanotheriplunger -intol pressure en'gag ment with' the moltenfglass V.and .by. pressureLcn'.n saidf. other plunger pressing moltenV glass 4between' 'i the Vblock andthe plunger'to buildup/the said; op-1 posite surface. toftlie Vrequisite vshapeand. distancef l.

fromrtheurst mentioned surface vof theslolock1 to.v reflect incident light iingthe @general directionof the light-sourc-erbut -Wi'th a slight spread, and si. D multanejously. lpressing'ithe vrest;'offfthefimass 'of z molten glass intothe shape of a light transmitting `l lamp. lens. i i 111 I7; j; 41;.Themethod of making ay lamp lens' for trans."-. mitting 4lightof ai-danger indicating colori andiior;` y reflecting incident lightin the generaldirectionl of i imparting .the danger .indicating colo'rpto themeilectedilight; which-method comprises forming .al block vof, transparent.flensfiorming material .With one surface thereofoffztherequisite curvature to form the reiiecting portion jof Ythe,`A lens, and '.with

the opposite surface 'deviatingfrom'theg necessary shape and location for gautocol limating', reflection,"V the-deviation bein'gcnejof undersize, placing said block ing-a moldi With; its aiccuratelyiormedg sure e .mebliodfofmakinefia f1ens;iwhiich.. ccm prises forming tendens part @transparent i glassjwith onegsurfa-ce, thereofithen requisite curvaturekand; with the A opposite 'surface A closr-:ito said curved f surface `than @is 1 necessary for lautocollimating .ireection,; placing said f button in fa moldiiwith` said, one'y surfaceri'n engagement with' thefmoldzfwall';.placing'in said mold a mass off moltenrglass, bringingiamolding :plungerin'tospo: sition opposite toi and accuratelyLspacedIf-romisaid5 onei'surfacefiandabringingf another plunger intoy pressure engagement with the mass of colored glass to press the molten glass between the ibut-4 ton and the first plunger to mold a layer of molten glass over the button to" bring the second 'mene tioned surface of the lens to the requisite curvae i ture a r-elative distance'from the first surface:

6. The method of making a lens whichfcome prises forming a part of the lens with at least one optical surface of the shape it is to have 'in the finished lens, placing said preformed partinga mold, then molding the rest of the lens around said preformed part with the preformed part 'ex'- tending almost but not quite through the "said e subsequently moldedpart, Land in the molding operation fusingr a layer of the molding-material over a surface of the irst lens part opposite ithe said vrst mentioned optical surface and in vthe molding operation mechanically shaping the out.

side of said layer to the requisite surface 'shape and position it is to have `,in the ultimate vlens by pressing aplunger into engagement with theouter surface of said layer and maintaining the press-Y ing surface of the plunger at-a fixed distance from said first mentioned'optical surface.

'7. The method of making a lens for transmitting light of a danger indicating color and for reflecting incident light in the general direction ofthe light source but fwith a slight'spread and imparting the danger indicating color to `the-reflected light, Whichmethod comprises 'forming-a1 block of transparent lens-forming material with one surface thereof ofthe requisite curvature Ito form the reilecting portion of the lens and with.

the opposite surface deviating from the'riecessary shape and location forauto-ccllimatingfreiiection, thedeviation being one of undersiz'e,

placing said block in 'a mold with its accurately formed surface in engagement with the mold wall andl its opposite surface in the-moldicavity, placing a Amass .of molten glass of a danger 3indicating color on said block andin 'an arfriountV in .excess of that required Ito build said und'ersized block up to its requiredsize, bringing amolding plunger into a fixed positionspacedfrom'l and oppcsiteto said opposite surface Iofthe block and pressing apart of the moltenglass between i the block and the plungerto buildup the-said opposite surface to the requisite'shape and distance from the 'first mentionedsurface of the blockto reflect incident light'in'the generaldi-- rection .of the light source but -Withfa slight spread, vand pressing the excess molten fglas'sf-out from between the block'and the plunger.

8.t The method offmak'ing e 1amp lens ro'rftra'nsmitting light ofa danger indicating vcolor and for reflecting incident light in the general dire'ctih of the light sourcebut with al slight spread andv imparting the danger indicating color to there'- ilected light, which method comprisesformingJeJ blockfof transparent lenseforming material with one surface thereof of the requisitecurvature 'to form the reflecting portion of thelens-and-with the opposite surface deviating from the Vnecessary shape and location for autocollimatingreflection, the deviation being one of undersizeplacingsaid block in a mold with its vaccurately'formed suri face in engagement-with the mold wall a'ndits' opposite surface inthe Imold cavity,placinga4 mass of molten glass of "a danger indicating-dolor in said mold cavits7 .and in an amount in'ex'ce'ss y of that required tobuild saidundersizedblock up to its required sizefbringingza molding plunger into `a fixed position spacedA from and voppositeito y said opposite surface of the block,- bringing an--I other plunger into pressure `'engagement-F with the molten glass and byy pressure on said other plunger pressinge .part fof sai'd mass ofy molten glassbetween the. block andthe plunger to build up the said opposite surface to the 'requisite shape .anddistance from the first mentioned surface and imparting the danger indicating 'color to the reflected light, which method comprises forming a block of transparent lens-lfmingirnate'rial 'with one surface thereof of the requisite "curvature to form the 'refiectingportion lof the lens l"and `lwith the opposite surface deviating from 'the necessary shape and location forvautocollimating re-A flection, the deviation being 'one of undersize, placing said block 'in "a mold with its accurately formed surface in engagement 4with thefmold wall and its oppositesurface 'inthe mold cavity, lplacying amass of molten glass of a danger indicating c0101 in said A'mold Yctn/ity and r"in 'an amount in excess of that required to 'build said undersized block upto its? 'requiredsiza bringing a 'molding plunger into a fixed position spaced from andf'op- "posite to ysaid'foppcsite surface of Athe block, `and pressing a :part 4cif `the vmolten rgl'ass -between the block and the 'plunger 'itc lbuild up the said iopposite surface `exactly to the requisite shape :and distance from the first mentionedfsurfacefof the block 'to reflect incident flight in the general ldirection of'the-lightfsource'but with--a-slight spread, and's'imultaneou'slylpressing the rest of the 'mass ofmolten .glass into vthe shape of lafli'gl'ft t1-ans- :mitting `lamp lens.v

1o. frhe'method-cf making-aliens which comprises forming `a button lensipart o'f transparent glass with one `surfaceythereof of vthe requisite curvature rand -with ltheoppo'sitefsurface "closer to said curved `fsurface than-is .necessary [for vautocollinating reflection, placirig' rsaid ybutton in fa mold "with said one surface in engagement vwith the moidwalLplacinga mass of"molten.;glass on said Vbutton,:bringing a "m'oldingplunger intoiposition opposite to 'and accurately spaced 'from said fone -s'urf'ace *and bringing "another :plunger into'pressur'e engagement 'with' the mass' of' colored glassto: press affpart of the lfmoltenrgias's'between the buttonand "f the '-iirst plunge'rto 'mold :a layer of molten Sgl'ass" over the button f to i b'ring the second mentioned surface of the lens to the requisite curvature a relative L'distance from the `iirst :surface.

r-posit'e lsurfaces of v4c-ne part thereof Am'olded tothe requisite shape and' distance ap'artwitha higher amountofprecision than the rest ofthe lens, which 'method `comprises placing f moldable -len's forming'material' into' a mold,'b'ringing amolding plungerl into" arposition opposite to' and accurately spaced from 'that'ipart Tof the 'mold that'islto shape the'rst --m'entionedspart' of the' *l'ensjbrirrg infg 'another plunger-towards the 'mold fand-vinto molding l'pressing' engagement "with the l mass of moldingmaterial 'in the 4moldto shape'thefres't of 2 the lens land f to press f the vmolding 'material rml'y into 'allthe' space Vbetween the 4mold: and the first mentioned plunger.

11. Them-ethos' of making: a rens lwith :thefropi 

